The electronic real time exchange of messages, commonly known as “Chat”, is a widespread multi-user system, which allows users to remotely join into public or private discussions (Chat rooms). A chat room may in effect be displayed on a visual display device. Users may choose to participate, create and/or animate a chat room.
The users of the Chat system generally connect to a network comprising Chat servers. A user interface is commonly provided by a Chat client running on a personal computer. The user is offered a choice of chat rooms which may be identified by their discussion topics. The user may then either be invited to one of the available chat rooms, or request the server to let him join a determined chat room.
Known Chat services are commonly accessible through the internet network, and are accessed by means of chat clients that are specific to the available operating systems or may be executed by means of an internet browsing application under those operating systems.
Another way to access chat systems is currently available through digital television networks. A digital television network allows a digital television provider to broadcast information from a head end to subscribers. Each subscriber receives and decodes the information using a decoder in order to obtain and visualize corresponding services on his television set. The transmission of information may be done by way of terrestrial, satellite or cable network transmission.
The broadcast information generally comprises a plurality of services such as television programmes. A television programme typically gathers a video and/or an audio stream which may be understood as service components. Further service components may be data associated to the service.
The digital television network may provide a return link to return information from a subscriber to the digital television provider. The return link may be implemented in some cases through the network itself or else using a separate link such as for example a telephone connection established between the decoder and the provider by means of a telephone modem.
In order to implement a chat system in a digital television network, the subscriber is required to execute a chat client application on his decoder which processes the information received from the chat server and generates an appropriate display. The subscriber interacts with the chat client application and may select to join a chat room or any other option offered by the chat system. The subscriber's action is transmitted to the chat server through the return link. Hence the functionality offered by this digital television chat system is very similar to the functionalities known from the chat systems accessible over the Internet. In some instances, a chat server may be connected to a television network and Internet at the same time, and allow television subscribers to meet Internet clients in chat rooms.
The described chat systems use chat clients in which it is generally assumed that the user has a way to transmit information to the chat server either through the network or any other return link.
One particularity in television networks is that while the subscriber may permanently be able to receive information from the head end by way of broadcast, the return link may not necessarily be permanent. This is for example generally the case if the return link is established through a telephone connection.
Another particularity in television networks is that there may be specific services and programmes broadcast that may be subject to chat rooms.